I don't think the idea is to pick someone at random; it's more like speed dating, where you check for initial chemistry and aligned interests, and then decide if you want to take it further. Maybe you even do some due diligence and check references.

You're perhaps incurring more risk, compared to a friend/colleague you've known for 10 years; but then, there may also be a reward in connecting with a talented mind who you wouldn't've otherwise. (And it's not as though startups with close friends can't also go south in very ugly ways.)